1. Field of the Invention
The present invention concerns a contactless data transmission device, a valuable and/or security document which contains a data transmission device of this type, as well as a method for manufacturing the contactless data transmission device.
2. Brief Description of the Related Art
Contactless data transmission devices of this type are known. In order to achieve data storage and/or data processing in a valuable and/or security document, for example, electronic components have been integrated into the document for some time now with which the data can be stored and/or processed. According to the invention, one particularly means semiconductor chips when one refers to electronic components, in particular such chips which are suitable for storage and processing of data. The electronic components can, in particular, be electronic semiconductor circuit elements. The electronic components can particularly include so-called RFID chips which are suitable for contactless communication. RFID chips can be comparatively simple, for example only contain a serial number, and can contactlessly transmit this serial number upon activation or they can be memory chips with encryption as used, for example, in electronic travel documents. A contact field matrix consisting of a number of contact fields according to ISO 7816 can, for example, serve for data communication with external devices which are connected with the chip and, upon use of the document, for example a card, create an electrical contact to external data sources and data storage devices via input and output devices.
According to a further development of such valuable and/or security documents there are also contactless documents available which also contain electronic components for saving and processing data and which are also fitted with an antenna for exchange of data via input and output devices with external data sources. In this case, data are exchanged in this way with the components in the document by means of a read-write apparatus in such a way that the read-write apparatus generates an electromagnetic alternating field having a carrier frequency which is typically in the radio waves range, which is detected by the antenna in the document and converted into electrical signals which are passed on to the component. To output the data arising from the document the antenna generates a corresponding electromagnetic alternating field which is detected by the read-write apparatus. Such transponders or RFID (radio frequency identification device) systems have also been known for some time. Contactless communication can, for example, take place according to ISO 14443.
DE 10 2010 028 444 A1 shows a document with a chip and an antenna for inductive coupling of energy. The antenna of this document has an outer winding, at least one middle winding, and an inner winding, wherein the middle winding is arranged between the outer and the inner winding and the chip is electrically contacted with the outer and inner winding. The middle winding bridges the chip in a bridging area of the antenna. The antenna is formed as a spiral. The chip is mounted above the antenna windings using the flip-chip technique. The antenna windings can have a smaller width in the chip area than that in the remainder area of the windings.
DE 197 32 353 A1 A describes a contactless chip card, which has an insulating, one-piece, card body with a recess on one side of the card body, an electrically conductive coil which is directly arranged on surface areas of the side of the card body with at least one recess, as well as an unhoused chip, which is arranged in the recess. The chip connecting surfaces of the chip are electrically contacted with the connections for the coil by means of the flip-chip technique.
U.S. Pat. No. 6,522,308 B1 provides a coupling antenna which has one or more capacitors and is designed in the form of windings on a carrier. The capacitor is formed by a first and a second conductive surface and an insulating surface lying in-between. A resonant circuit is formed by interconnection of the antenna with the capacitor.
To provide for simplified and cost-effective manufacture of a transponder DE 102 58 670 A1 describes a structure with an electronic circuit and an antenna device which is formed by at least two commonly drivable oscillating circuits each with a coil, which are galvanically separated from one another. One of the oscillating circuits is galvanically connected with the electronic circuit. The other oscillating circuit has a capacitor. Both oscillating circuits can, for example, be arranged in various levels congruently one above the other or also interleaved. Preferably, each of the coils has only one single winding. The resonance frequency of the transponder depends on the number of oscillating circuits and on the resonance frequencies which the oscillating circuits would respectively individually have for operation which is decoupled from one another. It is smaller than the lowest resonance frequency of the individual oscillating circuits. It is stated that this allows the resonance frequency to be set optimally by the number and design of the individual oscillating circuits.
A resonant circuit is described in US 2008/0198078 A1 with an antenna for a resonant circuit which has spiral windings and with a module with an electronic chip. To adapt the resonance frequency of the antenna, it has, in a partial zone some distance apart from one another, spiral windings which differ from those in other partial zones. These distances can, in particular, be greater than those in the other partial zones.
US 2009/0315799 A1 furthermore describes an electronic unit, which has both an electronic circuit and an associated antenna. The antenna in turn has a loop which is connected with the electronic circuit, as well as a resonator which is coupled to the loop. The resonator is formed of conductive windings with free ends. It is stated that use of the resonator, on the one hand, amplifies the electrical signals and, on the other hand, creates greater flexibility as concerns the design of the antenna.
The transponders mentioned above do, however, prove to be disadvantageous since the investment required for their manufacture is relatively high. For example, manufacture of the transponder according to DE 102 58 670 A1 requires capacitors to be manufactured. This requires additional operational steps which increase the costs involved. The same applies for the antenna specified in U.S. Pat. No. 6,522,308 B1. The circuit shown in US 2009/0315799 A1 has the disadvantage that the resonance frequency achieved with the antenna arrangement is very high so that tuning of the circuit in a range which is required for commercial use (in the range of 30 kHz to 30 GHz, preferably 3 to 30 MHz, for example 13.56 MHz), is not possible or extremely difficult to achieve.
This being the case, there is the problem that manufacture of the known transponders is expensive and that the transponders may well not readily be usable in a prescribed frequency range. The technical problem on which the present invention is based lies in creating a contactless data transmission device according to ISO 14443 which is simple and economic to make and which can be used in a prescribed frequency range. It should also, in particular, be ensured that the data transmission device can exactly be adjusted/trimmed by simple means to the prescribed resonance frequency. Since one significant field of application of the present invention, is to also use the data transmission device in valuable and/or security documents, one must also ensure that the document cannot be manipulated. It is above all necessary to ensure that an electronic semiconductor chip contained in the document cannot be removed and manipulated or replaced by another chip without this manipulation being recognizable afterwards.